Multimode analytical instruments, also referred to as multimode readers, are apparatus that can perform multiple analytical assays in a single instrument. Standard multimode readers, used within the life science industry, can measure the most common types of assays (i.e. applications, such as fluorescence, luminescence, and absorbance) in a single instrument. The use of a single instrument to perform these assays is advantageous over using multiple dedicated instruments to perform the same measurements. This lies in the fact that a multimode reader can provide ease of use, a better price performance ratio, and require less bench top area than multiple instruments.
Multimode readers having a certain level of modularity are known. Further information on these instruments can be found in US Patent Application Nos. 2005/0012929; 2005/0105080; and US 2003/0048447, for example.
Generally, these instruments have built-in general purpose (i.e., white) light sources, such as halogen lamps and xenon flash lamps, and general purpose detectors such as photomultiplier tubes (PMTs) and silicon photodiodes. Also, in these instruments, optical filters have been mounted into wheels or slides, and application specific beamsplitters have been installed into slides, or into revolver like mechanisms.
However, with the above described instrumentation, performing a specific application means, from the hardware point of view, accessing a multitude of driven stages, at runtime, for selecting the correct combination and adjustment of filters, beamsplitters, apertures, and lightguides, for example. In these devices, enabling new applications of a given technology requires retrofitting specific optical filters and beamsplitters. Further, new configurations demand the correct definition for the new filters within the instrument control software.
Moreover, conventional multimode readers typically filter a light beam by utilizing either bandpass interference filters or monochromators. Systems employing monochromators may also employ an interference filter to improve the blocking of unwanted light or as an order-sorting filter. These filters may be bandpass, short-pass or long-pass filters, depending on the specific needs of the system. An advantage of an interference filter is that it can transmit a large-diameter light beam with very good blocking characteristics (e.g., elimination of unwanted colors of the light beam). However, interference filters employed in conventional multimode readers are not tunable, such that every wavelength requires a specific filter. On the other hand, systems with monochromators have the ability to tune wavelength, but limit the diameter of the light beam significantly. The blocking of unwanted colors of the light beam is also limited if just a single monochromator is employed. Blocking may be improved by adding a second filter element, i.e., another monochromator or an interference filter in the light path. The fundamental problem of the limited size of the entrance and exit slits of a monochromator cannot be resolved unless a very large monochromator could be built into a multimode reader, which is not practical due to size and cost. In theory, alternative technologies such as liquid crystal tunable filters (LCTFs) and acousto-optic tunable filters (AOTFs) might be integrated into multimode readers, but to do so would be cost-prohibitive.
Therefore, there is a need for an improved and more efficient multimode reader instrument. There is also a need for a multimode reader instrument that can change applications and have the identification of the programmed parameters for the new application be performed automatically. There is a also a need for a multimode reader instrument that can be easily upgraded for new types of applications. There is also a need for a multimode reader instrument having improved wavelength tuning capability.